The present invention pertains to solenoid operated directional valves such as are used in hydraulic systems to control the direction of hydraulic fluid flow and is more specifically directed to the electrical connector and terminal structure of such valves.
The cross referenced co-pending U.S. patent application Ser. No. 135,974, now U.S. Pat. No. 4,308,891, addresses a number of problems inherent in prior solenoid operated directional valves and provides a new and unique solution to those problems. The present invention in one respect represents a still further improvement in solenoid operated directional valves.
Some of the problems encountered with solenoid actuated directional valves prior to the inventions of the present and the cross referenced patent applications include: the difficulties of servicing the valves in the field and of installing them in relation to available electrical sources; the possibility that incorrect electrical connections may be made during assembly, installation, or maintenance of the valves; and the restrictions which might be imposed by pertinent local codes. For example, a valve might be mounted on a piece of equipment without knowledge of the direction from which the source of electric power is to be supplied and without knowledge of any mounting restrictions that may exist. In order to properly connect the valve to the available electric power supply it might be necessary to reorient the location where the supply wires enter the valve. In prior valves this typically involved some disassembly of the valve and a substantial amount of rewiring the individual lead wires of the various circuits. With this procedure the possibility existed that the lead wires might not be properly reconnected resulting in improper operation and the potential for damage to or failure of equipment.
The invention of the subject cross referenced U.S. patent application provides a new and unique solution to the problem of having to reorient the electrical connection to a solenoid valve, whereby reorientation can be accomplished expeditiously without the need to perform any rewiring of individual circuits but with full assurance that correct continuity of individual circuits will be maintained. A resultant benefit is that installation and maintenance costs can be reduced in the field. The invention of the cross referenced application also ensures that in the case of double solenoid valves having associated indicator lights which indicate which of the two solenoids is energized, each lamp will continue to be properly connected to the correct solenoid after reorientation.
The invention of the present application provides a solenoid operated directional valve of modular construction wherein electrical connections between the various component parts of the assembly are made integral and concurrent with the act of mounting the component parts together. With the modular construction there are no separate lead wires which have to be individually connected, and continuity of circuit operation is assured both at original assembly and after any subsequent reassembly for maintenance or modification purposes. Assembly time at the factory and maintenance time in the field are significantly reduced.
Furthermore, the invention provides a substantial degree of versatility both with respect to fulfilling individual customer requirements from the factory as well as for service, installation and/or modification purposes in the field. Depending upon requirements of a given customer, various features may be selectively incorporated into the valve as the customer wishes. This allows the manufacturing of the valve assembly to start with a base valve unit to which various options may be selectively added. Service inventory requirements can be simplified because it is unnecessary to stock a full range of unique complete valve assemblies. Rather, if a given model of valve assembly is desired, it may be developed from the base valve unit by simply adding the appropriate component parts, which may be done with expediency and once again without any separate lead wires to connect. Similarly, modifications may be made to remove optional features from a valve, and this likewise can be done with expediency and without any separate lead wires to rewire. In all instances continuity of circuitry is assured. Any modification, by way of either addition or subtraction of component parts, is accomplished in a non-destructive and waste-free fashion so that a valve assembly from which component parts are removed may at a later time either be used for its remaining component parts or rebuilt into a functional assembly of a desired configuration.
The invention also provides compatability with domestic and foreign requirements. For example, foreign requirements either mandatory or customarily accepted in the trade, may be somewhat different from corresponding U.S. requirements. With the present invention the base valve unit may be used for either foreign or domestic applications and the additional component parts may be selected with a view to the requirements of the particular application, be it foreign or domestic.
As an example of the substantial advantages and benefits of the present invention consider a situation where a conventional prior type of solenoid valve is installed in use in a manufacturing plant and requires service. Often the valve is in a poor location for access by maintenance personnel. In such a situation they may completely disconnect the wiring and hydraulic lines to the valve, remove the valve as a unit from its mounting and replace it with a new one, leaving the defective valve to be repaired at the bench. Such a procedure will usually involve a substantial amount of machine downtime, and furthermore it may require an appreciable amount of bench time to fix the defective valve. Such a procedure impairs the operating efficiency of the machine and of the plant. Moreover, in union plants the service procedure may require that both a hydraulic technician and an electrical technician be present because both electrical and hydraulic apparatus are involved. Where the valve must be rewired, the possibility exists that the electrical wires may not be properly reconnected, and this can lead to failure of the valve and/or associated equipment and contribute to further inefficiency.
If an attempt is made to service a faulty solenoid valve of the prior art type without removing it as a unit from the equipment on which it is mounted, other problems may arise. For example, if only a defective solenoid needs to be replaced, the construction may be such that a significant amount of disassembly is needed possibly encompassing more than just the solenoid per se. This could lead to misconnected wires upon reassembly and to other problems. Also certain solenoids are susceptible to damage during the re-installation process. For example, a solenoid is secured to the valve body by means of a nut which is tightened against the solenoid casing. If care is not taken in tightening the nut, it may be overtorqued to the point of cracking the solenoid casing. In addition to the destruction of the solenoid in such a situation, further downtime results.
From these foregoing examples it can be seen that prior valves do present inefficiencies when considered in the context of installation and maintenance at the plant site.
The present invention by contrast substantially alleviates or eliminates entirely the problems of prior valves. For example, if it is necessary to service only the electrical portion of the valve, such service can be conveniently done without removal of the valve from the machine and having to disconnect hydraulic lines. Furthermore, such service can be accomplished without the necessity of disconnecting individual wires and reconnecting them later. If it is necessary to replace only a solenoid, the present invention allows a solenoid to be replaced simply by unplugging the defective solenoid and plugging in a new one. Likewise if it is necessary to service the electrical structure which forms the electrical connection from the solenoid to the electrical source, only the junction box cover need be removed to provide access to the component parts which can then be conveniently removed and replaced without having to make any wiring disconnections and reconnections.
The foregoing features, advantages and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims wherein like reference numerals designate like parts in the various drawing figures. The drawings disclose preferred embodiments of the invention according to the best mode presently contemplated in carrying out the invention.